1. Field of the Invention
The present invention relates to a packet communication method.
2. Description of the Related Art
Generally, technologies for guaranteeing a communication band and a communication speed and for compensating communication errors over network are collectively called Quality of Service (QoS). More specifically, Automatic Repeat Request (ARQ) and Forward Error Correction (FEC) are known and used in communicating voice and moving image data in the Real-time Transport Protocol (RTP) format. ARQ is a technique for retransmitting a packet that was not received by a reception device due to communication error. FEC is a technique for recovering a packet that was not normally received due to communication error, using redundant data attached to the data.
Hybrid ARQ, the combination of ARQ and FEC, is also known. For example, Japanese Patent Application Laid-Open No. 2004-159042 discusses retransmission of only a packet that could not be recovered using FEC, by ARQ.
The retransmitted packet, however, increases the volume of communication.
For example, when there are a number of missing packets that could not be recovered using FECs, the retransmission of all of the missing packets may drastically increase a volume of communication. Such missing packets may be caused by congestion on the network. In such a case, it is desirable to decrease the volume of communication as much as possible.